OK, upon further review (8 1/2 years later), about 50% thicker. Kreskin explains to the audience that, in her left hand, host Kathy Fountain is holding just the Hearts ("Ace through King") from an ordinary deck of cards (she has not looked at them). But, another closeup shot of the cards in her hand, as compared to a hand definitely holding just the Ace through King of Hearts from a standard deck (I was supervising this shot), reveals that Fountain is holding about 50% more cards than indicated by Kreeskin.

Resume reading the Kreskin article